Field of the Invention
This invention relates to adjustable clamps formed primarily of extrusions. In particular it relates to an adjustable clamp in which two extrusions are joined together by extruded portions thereof that serve as retaining members to hold the two extrusions together and also serve as a hinge structure that allows limited pivotal movement of the extrusions relative to each other. The pivotal operations is controlled by a bolt that extends through a clearance hole in one of the extrusions and threadedly engages a threaded hole in the other extrusion at a location so that tightening the bolt draws pressure pads on the two extrusions toward each other and, at the same time, draws the retaining members more firmly into engagement with each other.
The co-pending United States Patent Application of Samuel A. Hochstetler and Thomas R. Turner, Ser. No. 467,024, filed Feb. 16, 1983, describes an antenna clamp that includes two extrusions, one a flanged plate and other a locking plate, joined and hinged together by a bead along one edge of the locking plate and a partially closed slot on the flanged plate. One side of the slot is defined by an extruded ridge, and the other side by an extruded flap that extends part way around the bead and terminates close enough to the ridge so that the gap between the edge of the flap and the ridge is narrower than the width of the bead but greater than the thickness of that part of the locking plate adjoining the bead.
The first extrusion is free to pivot to a limited extent within the slot but can only be separated from the second extrusion by movement of the bead longitudinally along the slot. Such longitudinal movement is prevented, and the two extrusions are urged toward each other and into clamping engagement with the rain gutter on the automobile, by screws that pass through clearance holes in the flanged plate and engage threaded holes in the locking plate.
U.S. Pat. No. 4,147,257, issued Apr. 3, 1979 to Zippel, describes another extruded clamp comprising two essentially flat clamping plates that are essentially parallel to each other and spaced apart just enough to grip a pad of lamellar material between them. One of the plates has a flange along one edge to give it a J-shaped configuration, and the edge of this flange has an extruded channel to receive and to hold a bead extruded along one edge of the other clamping plate. The latter plate has a flange near the bead and extending perpendicularly from that plate, and a threaded shaft extends through clearance holes in the flanges on the two clamping plates. The shaft has a cross bar at one end to prevent it from rotating, and a wing nut screwed onto the other end to exert pressure on the clamp plates by way of the flanges.
U.S. Pat. No. 3,920,235 issued Nov. 18, 1975 to Hermanns describes another clamping structure in which the two main members are extruded and are provided with an integrally extruded retaining hinge comprising a bead along one edge of one of the clamping members and a matching channel in the other clamping member. However, instead of drawing the clamping members together by a suitably placed bolt, the clamping pressure between them is obtained by forcing them apart and in a direction such as to tend to pull the bead transversely out of the channel rather than to press it more firmly into the channel.
U.S. Pat. No. 2,182,480 issued Dec. 5, 1939 to Lowry shows still another clamp comprising two extruded members, both of which are generally L-shaped. Although pressure to apply clamping force between these two members is generated by a screw and nut arrangement that extends through matching parts of the L-shaped members, the screw is held by separate nuts that engage the respective members. Furthermore, the hinge that defines the axis for pivotal movement of one of the members relative to the other is formed only by a knife edge on one of the L-shaped members that rests in a V-shaped groove in the other. Thus, when there is no work piece to be grasped between the clamping surfaces, the two L-shaped members are not properly held in pivotal engagement with each other.